Cereal flour fractionation processes



Feb.. 12, 1963 T. A. RozsA ETAL CEREAL FLOUR FRACTIONATION PROCESSES Original Filed Nov. 22, 1954 4 Sheets-Sheet il .SOFT W/'AT SCALE 50 ro /AR WHEAT PROTEIN TARCH .SIZE LARGEST 5125 MAJoR /r/G. 5 AND LlNiAL AND ANDMlNoR SHAPE DlMEN-SWN .SHAPE DIAMETER F'D UNITS 11.45 Rnor. /0.9 M0157'. [00% 407415 Feb. 12, 1963 T. A. RozsA ETAL 3,077,408

CEREAL FLOUR FRACTIONATION PROCESSES Original Filed Nov. 22, 1954 4 Sheets-Sheet 2 Feb. 12, 1963 T. A. RozsA ETAL 3,077,408

CEREAL FLOUR FRACTIONATION PROCESSES Original Filed Nov. 2.2, 1954 4 Sheets-Sheet 3 @wf/ FQAcr/a/v H480 Wwf/17 oA/esi FRAU/am HAAP@ w//far f/G. /4 FIA/ER rl/A/v Humm. ud mmm: .vu

Feb. 12, 1963 T. A. RozsA ETAI. 3,077,408'

CEREAL FLOUR FRACTIONATION PROCESSES Original Filed Nov. 22, 1954 4 Sheets-Sheet 4 56./7 e@ e, o gg o O 2Q@ O o @o com "Gv 3,977,408 Patented Feb. 12, 1963 ice cansar moon nncrioNArroN rnocnssns Tibor A. Rozsa, Chastain G. Harrel, William Truman Manning, Arlin B. Ward, and Rezsoe Gracza, all of Minneapolis, Minn., assignurs to The Pillsbury Company, Minneapolis, Minn., a corporation of Delaware Continuation of application Ser. No. 470,244, Nov. 22,

1954. This application Dec. 28, 1959, Ser. No. 862,099 6 Claims. (Cl. 99-93) This invention relates to the fractionation of milled, cereal ours with the attendant production commercially and economically, from a single flour source, of two or more premium products having commercial signin-:ance and each having materially different chemical and physical characteristics, as well as being signicantly different from any products of the prior art.

Basically, our invention consists in the discovery that milled, cereal our stock may be consistently fractionated by air separation at heretofore unknown ranges of criticalcut, to withdraw from the parent flour stock in one fraction substantially all discrete, protein-matter particles, and simultaneously to produce a relatively large-volume fraction, high in starch content and substantially depleted of discrete protein particles and the matters which contribute to high ash characteristics.

More specifically, our invention comprises novel air separation methods for effecting consistently and accurately the fractionation defined in the preceding paragraph together with the discovery of fluid-dynamic characteristics and measurements of the various particles contained in flour stocks and with the inclusion therein of certain heretofore unseparated protein-matter particles.

A number of projects have been undertaken to investigate fractionation of milled Hour stocks with a View t separating our into fractions having commercial signicance. Recent reports disclosing developments in fractionation include the published Kansas State College Agricultural Experiment Station Technical Report, April 1950, by I. A. Shellenberg, Frank W. Wichser and R. O. Pence, and a report by Rae H. Harris of North Dakota Agricultural Experiment Station, Fargo, North Dakota, entitled Flour Particle Size as Influenced by Wheat Variety and Location of Growth.

Prior to our invention, none of the known authorities discovered, first, that the most concentrated protein-matter particles of cereal Hour are contained within the fines or throughs of the sub-sieve size (passable through the finest W. S. Tyler Company test sieve having 40G meshes to the linear inch and of what is termed 38 micron size) and that, secondly, such minute protein-matter particles may substantially all be separated from the parent flour stock by air separation with the help of fluid-dynamic measurements and principles. In fact, the exhaustive Wichser report states that the more concentrated proteins are found in wheat particles over 38 microns in size and which will not pass through the 400 mesh experimental sieve.

The application of our discoveries to commercial production has been facilitated and made standard after our development of a novel method of unit measurement for duid-dynamic characteristics of the various particles of cereal flours. Such measurement expressed in units are hereinafter referred to as F-D units.

The foregoing features and other accomplishments of our invention will be more apparent from the following description, made in connection with the accompanying drawings wherein like reference numerals refer to the same or corresponding parts in the several views and in which:

FIGURE l is a plan view on highly magnified f approximately 250 times) scale, showing typical fragments of endosperm cells of soft wheat with the individual starch granules imbedded in a homogeneous, somewhat translucent protein matrix; n

FIGURE 2 is a similar view showing several typical fragments of hard wheat endosperm cells wherein the protein matrix is less translucent;

FIGURE 3 is a diagrammatic chart summarizing certain findings, proofs and results obtained by sedimentation test of the air separated, smallest wheat flour particles with subsequent powerful microscopic examination of such particles from predetermined strata in the lower collecting end of a gravimetrically and centrifugally actuated sedimentation tube;

FIGURE 4 is a simple flow diagram illustrating diagrammatically the carrying out of a simple embodiment of our invention;

FIGURE 5 is a simplified flow diagram illustrating the i index 1.505) to obtain photo-micrographs from which said illustrations were made;

FIGURES 8 and 9 illustrate, on a similar scale of magnification, typical particles and particle distribution of the fine fractions obtained on the soft wheat and hard wheat samples respectively illustrated in FIGURES 6 and 7 through the utilization of our invention;

FIGURES 10 and 11 illustrate, on a similar scale Of magnification, typical particles and particle distribution of the coarse fractions obtained from soft wheat and hard wheat flour stock or samples illustrated in FIGURES 6 and 7 through the employment of our invention;

FIGURES 12 and 13 illustrate the fine and coarse fractions respectively on a similar scale of magnification, of hard wheat liour resulting from a second-stage air separation of the coarse fraction shown in FIGURE 11 on a critical-cut of 72 F-D units. The said fractions resulted from the process diagrammed in the ow sheet of FIG- URE 5, FIGURE 12 showing the medium fraction from. said last mentioned cut, and FIGURE 13 showing the coarser fraction from said cut;

FIGURES 14 and 15 are graphs illustrating our novel method of determining critical-cut through air separation and eiciency of the respective critical-cut separations;

FIGURES 16 to 18, inclusive, illustrate on a scale of magnification indicated by the micron scale underlying FIGURE 16 a parent soft wheat our material, the fine fraction obtained for protein concentration and the coarse fraction respectively obtained in a single-stage air separation operation, embodying oui invention, at a critical-cut of 161/2 F-D units;

FIGURE 19 is a diagrammatic view including an -abstract sketch on greatly enlarged scale of a particular protein-matter particle with legends and symbols correlating applicants explanation of relative shape factors with subsequent definitions thereof in Appendix C; and

FIGURE 20 is a diagrammatic View illustrating velocity vectors and force vectors acting upon a certain particle in general vortex-type of air classifiers, where the forces in radial direction, are in equilibrium (referred to in Appendix B).

We believe we are the first to discover in commercially milled, cereal flour stocks, the existence of a large number of discrete, extremely fine, highly concentrated, protein particles. The said particles contain an average of 93% protein, on a dry basis. The 7% not accounted for represents a small percentage of lipoids, mineral matter with a trace of carbohydrates and cellular wall material.

We also believe we are the first to discover any method o1'- means 'for substantially.concentrating protein-matter particles from a flour stock by dry process.

As a result of our discoveries and our novel air separation methods, unexpected results (new products) as cornpared to any other existing classifying procedures have been attained. Classification by air liow or fluid-dynamic principles use shape, size and density simultaneously in their complex principles of classification. Classification meth-od by sieve and sifter process is objectionable and inaccurate for several reasons, to Wit:

(1) Because of variations and different levels of moisture content in the stock, with the resultant changes or variations in electrostatic effects;

`(2) Because of variations or change in the feed rate;

(3) Because of varying fat content of the stock utilized;

`(4) Because of the shifting motion or gyration of the sieves often deecting or hindering passage of particles through the sieve openings;

(5) Because sieve openings provide a measurement based, not even on three dimensions of the particles, but only on two dimensions, whereby elongated particles may lodge crosswise of the openings. It will be obvious that two dimensions cannot satisfactorily represent particle size;

(6) No perfect bolting cloth exists and the inaccuracy of the disposition of the respective cross textile filaments is increased by continuous use.

The foregoing limitations and objections result in a very imperfect classification through sieve operations as judged by the sharpness of separation, which is considered to be a criterion of efiiciency. The result of sieve separation is that many oversized particles remain with the throughs and even a greater proportion of under-sized particles remain in the overs.

In our discoveries, efiicient air separation is used at unexpected and newly discovered critical-cuts. The critical-cut of commercial air separation as used herein is the graphically derived particle size, expressed in our F-"D units, at which the total percentage of the oversize particles in the fine fraction and the percentage of the undersizeparticles in the coarse fraction are at a minimum. An explanation of how we determine critical-cut graphically is given later herein.

For a long period of time, we carried `out an exhaustive series of air separation tests on conventionally milled cereal fiours including soft and hard wheat, rye, barley, corn and durum and rice. In such tests with the use of several commercial air separators or classifiers, we varied the several adjustments to successively vary critical-cuts upon the flour stocks utilized. During such experiments, where continuously smaller fractions were drawn off from the parent flour stock, a point was reached below subsieve size range where, contrary to the teachings of the prior art, protein content in the small and fine fraction withdrawn, by chemical analyses, was increasing at a rapid rate as our critical-cut decreased. Such unexpected discovery led to many tests of both the finer (and much smaller) fraction and the larger fraction produced in numerous instances and further led to microscopic examination of a great number of fractions separated.

We then realized, because of the great variety of shapes and sizes and further differences in density of typical flour particles, that a method and unit standard for evaluating the several fluid-dynamic characteristics was essential to determine and define the discoveries we had made. The factors of density, size and shape need to be evaluated at first individually and then together, and/or postulated to define our invention in critical terms.

With the utilization of fluid-dynamic, sedimentation tests carried out under the method and with the apparatus disclosed in the United States patent application of Kennetli` Whitby, Serial Number 329,411 (assigned to our assignee, Pillsbury Mills, Inc.), we were able to devise a.y new method of duid-dynamic .evaluation of the various particles found in cereal hour-stocks, taking into consideration density, size and shape and expressing such flowdynamic characteristics in measurable units. Said method and unit evaluation has been previously referred to and the mathematical basis for the same is carefully explained in the appendix hereto constituting a part of the detailed description hereof and positioned ahead of the claims. The units of measurement shall be referred to hereafter as li-D units.

In efficient, commercial air separators, several adjustments are available to vary the critical-cut of separation. They include the following:

(l) In the case of rotary separators or classifiers, the rpm. of the classifier rotor; in the case of classifiers which do not employ a rotor, the variance in the tangential velocity of the particles. Such changes vary the centrifugal force action on the particles.

(2) The speed of air dow, or cubic feet per minute through the classifier. vary the centerward component of drag on the particles.

(3) The rate of feed supply lor cwt. per liour of material fed to the air separator. In general, increasing the feed rate slightly lowers the critical-particle size.

(4) Mechanical elements now on several types of air separators and which may be added to others to vary the directional angle of entering air currents.

(5) In the case of rotary classifiers having more-or-less radial blades adjacent their peripheries, the inside and outside radii of such blades.

(6) Variance in the diameter of the air and fine particle discharge passage (sometimes referred to as the fan inlet opening) between the classifier zone and the fan.

(7) Variance in other structural elements of the classi-v fier.

In completing our discoveries and invention, we made use of the variable adjustments of efficient, commercial,A air separators available to us, and correlated with such adjustments our evaluation of Huid-dynamic characteristics and measurements of particles, and then were able to attain optimum results in the withdrawal of protein-' matter particles from milled, cereal fiour stocks as well as in obtaining maximum depletion of protein-matter particles and matters contributing to high ash-content of the coarser fraction. Our discoveries of the inherent characteristics, sizes and shape of discrete, pure, protein particles and the fluid-dynamicrelation of the same with discrete starch-granule particles constituted an important factor in the perfection of our invention. An explanation of velocity and force conditions when particles are subjected to vortex-type air separation, is set forth in Appendix B hereof.

While, with the proper adjustments along the several lines previously indicated, numerous air separating machines and air classifiers are adequate for consistently and accurately carrying out the different steps of our new processes, we list below several commercial machines which have been available and utilized by us and properly adjusted to produce successful results and the novel products of our invention.

(1) Sturtevant Whirlwind Centrifugal Separator, manufactured by Sturdevant Mill Co., of Boston, Mass.

(2) Commercial structures of the Carter Patent No. 2,633,930 (licensed to Superior Separator Company of Hopkins, Minn.);

(3) Improved centripetal of classifier embodying the machine disclosed in United States patent application, Serial No. 306,126, of H. G. Lykken;

(4) Commercial analyzer machine (for experimental use) disclosed in U.S. Patent No. 2,019,507, Apparatus for Fractionating Finely Divided Material, of Paul S. Roller.

We found we were able to define, in terms of fluiddynamic units (F-D units) the ranges ofcritical-cut-for optimum results, first in the concentration of maximum Adjustment of this factor will protein-matter ingredients and secondly in the depletion, in the coarser and larger fraction, of prote;n and high ash-containing ingredients. These ranges are as follows:

For protein concentration- Hard wheat flour-lS to 30 FD units 5 Soft wheat flour-l5 to 25 F-D units White rye hourto 25 F-D units Dark rye flour-l8 to 25 F-D units Corn flour-ZO to 35 F-D units For protein and ash depletion in coarse fraction- Hard wheat flourto 40 F-D units Soft Wheat flour-2O to 35 F-D units White rye flour-20 to 35 F-D units Dark rye flour- 20 to 35 F-D units Corn ilour-25 to 40 PLD units In connection with the above defined ranges, it is to be remembered that the harder and higher protein endosperm has poorer grindability. Consequently, it is usually ground to coarser average particle size iiour. In the above ranges, where hard Wheat fragments are specified, such include durum.

n discovering the range of critical-cuts for maximum protein concentration and optimum protein and ash depletion for various milled flour stocks by utilization of efficient air separation, We unexpectedly discovered the existence of a point or zone hereafter referred to as the neutral critical-cut, above which air separation at successively higher critical-cuts will consistently produce a fine fraction having a protein content smaller than the coarser fraction produced. Below said neutral cut, all critical-cuts successively made on a decreasing scale will result in production, as has been previously indicated, of a fine fraction having protein content substantially higher than the protein content of the coarser fraction obtained in each instance. In the said zone, a criticalcut or critical-cuts carried out by our exhaustive tests show that the air-separated line fraction and the coarse fraction obtained simultaneously have the same protein content as the parent stock. The optimum critical-cut ranges for protein concentration of the tine fraction and protein and ash depletion of the coarse fraction defined on the preceding page are all substantially below said neutral critical-cut or zone and, as previously stated, the fine fractions are consistently of average particle size substantially below the average particle size by Fisher of the throughs obtained in sieve and sifting operations by use of the finest (400 mesh lineal inch) experimental sieve available.

The neutral critical-cut ranges for the various milled cereal iiour stocks as discovered by us, are as follows: For soft wheat hours-42 to 60 F-D units For hard wheat flours (including durum)-51 to 69 F-D units F or white rye Hours-52 to 68 F-D units For dark rye hours-40 to 56 F-D units For corn hours- 36 to 52 F-D units Theoretically and scientifically, all air separations made on critical-cuts above said neutral critical-cut result in fractionation of a cereal, flour stock wherein the fraction having the smaller or finer particle size contains less protein than the other fraction having coarser particle size. The reverse of such rule or finding is true relative to all air separations made on critical-cuts below the neutral critical-cut to the end that there the finer fraction always contains more protein than the coarser fraction. Such we find is consistent with the morphology of cereal endosperm particles. These discoveries are directly contrary to the reports and findings of experiments in known prior art where a sieve separation was utilized in one or more stages of the experiment. We have definitely concluded that critical-air separations within the scope of our discoveries brought about particle size classiiication of a very different character than separations performed where a screen or sifter is used. 75

Cil

`We further found, through exhaustive analyses of our fractions produced by critical-air separations within the ranges heretofore defined in column 5, lines 6-18 hereof, that the respective products have novel and different chemical and physical characteristics as contrasted with any cereal flour fractions produced before our discovery, and furthermore, gave substantially improved and new end results in the production of baked products made from our novel fractions.

The selected critical-cut within the ranges heretofore set forth is dependent upon the type of the cereal flour and type and intensity of grinding applied. Different grinding machines produce different particle shapes and the particle shape inuences the critical-cut. In general, the hner the granulation of the parent our material, the lower will be the critical-cut within the ranges expressed, and the higher the protein content of the parent material, the higher will be the critical-cut Within the ranges eX- pressed.

Generally speaking, the optimum amount of the tine fraction pulled out of the parent flour material for protein concentration varies between 3% and 17% of the total flour stock fed into the properly regulated air classifier. The coarser the parent stock, the less the proportion of optimum protein, iine fraction obtainable. For example, we have made air separations at the appropriate criticalcut upon middlings and there the ne fraction removed was only 2% and contained 18.5% protein, whereas the protein content of the coarse fraction was 9.6% and the protein content of the parent stock was 9.8% (all calculated on 14% moisture basis). When flour milled from the same wheat stock having a protein content of 10.3% was separated at the optimum critical-cut in accordance with our invention, the removed fine fraction constitutes 10% of the original stock and had a protein content of 20.6% while the coarse fraction had a protein content of 9.6%.

The smaller and liner fractions obtained by our processes, within the respective critical cut ranges set forthV in column 5, lines 6-18, both for protein concentration and when depletion of protein and ash is desired, contain most of the lipoids as well as mold spore of the parent stock. From our knowledge and our analysis microscopically of the line fractions obtained, we have determined that With eflicient air separators capable of making critical cuts down to 8 F-D units, a large percentage of the high ash-contributing particles of the parent stock may be withdrawn at a critical cut range between 8 to 16 F-D units without substantially depleting the parent stock of protein matter particles.

In order to obtain the hereindescribed optimum results (maximum protein concentration and depletion in the respective two fractions), in addition to the critical-cut data, it is essential that knowledge for the performance of separation concerning the products be as complete as possible and that sharpness of classilicaiton should be the goal.

To this end, in evaluating our discovery after conception of our system of duid-dynamic evaluation of the various and sundry particles and expression thereof in F-D units, it was desirable to plot the results of tests to show size frequency distribution and to determine criticalcuts and the efficiency of the separation.

Accordingly, we conceived and worked out a method of evaluation of air separator performance and criticalcuts which constitutes a part of our invention and enables us to classify and define in terms of said fluid-dynamic units (F-D units), the critical-cuts and the eiciency of separation in obtaining our desired results. To illustrate the method of such evaluation which we conceived, two graphs are shown in FIGURES 14 and 15 of' the drawings of this application, laid out on semi-logarithmic graph paper which, for our purposes, seems most desirable. The sedimentation tests reveal how many percent of the particles in the fine fraction are coarser than the size at which normes the separation was supposed to take place. Similarly, said tests revealed to us how many percent of the particles in the coarser fraction are finer than the size at which the separation was intended. On the horizontal lines of the graph shown in FIGURES 14 and 15, the particle size is plotted in F-D units and the vertical line shows in percentages what proportion of the sample is finer than the corresponding particle size. The Whitby sedimentation test is particularly suitable for the measurements of air-separator performance since both air separator and liquid sedimentation operate on the same general principle.

In FIGURE 14, we illustrate an over-simplified case of a hypothetical, ideal separation; an illustration, of course, of abstractly perfect performance with 100% sharp separation. Every particle in the tine fraction is ner than 47 F-D units and every particle in the coarse fraction is coarser than a measurement of 47 F-D units. We choose to call the particle size at which such separations take place, the critical-cut. It will be noted that a curve has been plotted for both the tine fraction and the coarse fraction. To determine from the two curves the critical-cut, we select that particle size from the curves at which the over-size particles in the tine fraction and the under-size particles in the coarse fraction are at minimum and which, on the graph, is the vertical line coincident where the two cumulative curves are the farthest apart. We draw a vertical line in FIGURE 14 along an F-D unit line of 47, indicating the critical-cut expressed in our fluiddynamic units. We find that such distance between the two curves on said perpendicular line, measures the sharpness of separation, in that this line is parallel to the line of the graph which denotes the percentage tiner than the corresponding particle size on the line. We can, therefore, read the distance between the two cumulative curves in the same scale which is plotted on the axis and read the sharpness of the separation directly in percentage.

The second graph illustrated in FlGURE l shows the actual performance in our experience of an efficient air separation when adjusted as previously indicated to commercial high efficiency. The cumulative particle size curve of the coarse fraction (representing 85% of the original material) is plotted and the second or upper curve is plotted representing particle size distribution of the smaller and tiner fraction constituting of the sample or parent stock material air classified. By such plotting of actual air separator performance to determine the critical particle size of separation, we select that particle size from the curves at which the total of the over-size percentage in the tine fraction and the undersize percentage in the coarse fraction are at their minimum. That is what a critical separation should accomplish, self evidently at such a critical particle size (31 F-D units in this instance) the vertical distance is greatest between the two cumulative curves. This vertical distance is the sharpness of the separation-81% in this instance. The over-size in the line fraction may be read on the graph as 6% and the undersize particles in the coarse fraction are shown by the graph to constitute 13%. lt is very easy and rapid to iind, with a straight edge, the place of the greatest vertical distance between the cumulative curves of the coarse and line fraction. The foregoing is our conceived method for determing at what critical particle size expressed in fluid-dynamic units (F-D units) the separation took place and, furthermore, what the eticiency or sharpness of the separation amounted to.

Having now generally disclosed our invention which comprises several novel discoveries and which includes the essential method steps, ranges of critical-cuts and the novel and patentable resultant products or flour fractionations, we will not point out more speciiically, the results obtained, the significance of our discoveries and some of the proofs of the substantially complete separation from milled cereal flour stocks of the discrete-protein-matter particles.

With the use of our evaluation of huid-dynamic characteristics expressed in our F-D units and our determination of the critical-cuts (expressed in F-D units) and eiciency of adjusted vortex-type air classitiers, we have been able to commercially repeat our methods on the milled flours of hard wheat, soft wheat and rye and, in addition, have found our method to be highly efficient in the treatment of corn tlour to remove or concentrate fat, ash and protein matter. It must, of course, be remembered that many fragments of endosperm cells as well as agglomerates of protein-starch are present in the available milled flour stocks and, unless further broken up through attriction of the particles in the air classification, will remain with the coarse fraction obtained in our method. Some attrition reduction of particles by impact inherently does take place in air separation and our tabulation of results indicates that at least some of the agglomerates are broken down into discrete starch granules and discrete protein-matter particles.

At the critical-cut ranges heretofore specified for soft wheat fractionation in many cases the percentage protein content of the fine fraction can be increased to 21/2 times that of the original ilour stocks, the increase in protein of the tine fraction as compared with the milled flour stock utilized being consistently about two-fold in fractionating with our method hard wheat iiour stocks. In the case of white rye tlour, the concentration of protein of the tine fraction obtainable at the critical-cuts hereafter specified in examples given, approximates twice that of the original rye flour.

Referring now to FIGURES 1 and 2 of the drawings, these were produced by us as a result of our own intensive observations on visual examination microscopically at magnirications (ranging with different microscopes from to 322 times the actual size). The illustrations of FIGURES 1 and 2 are also in strict accord with existing authorities on the morphology of cereal endosperm. The symmetrical or ovoid granules we know are starch granules. The encysting portions in which these granules are imbedded we know to be generally homogeneous protein matter and the fats normally accompanying the same, this constituting in endosperm cells of cereal grains, a matrix or mass in which the ellipsoid, Starch granules (varying substantially in size) are originally imbedded and retained. The starch granules are Very closely spaced in the imbedding matrix and this protein matter generally is narrowed very appreciabl-y between the most adjacent portions of adjacent starch granules and at such narrowed portions, is almost always thinner or narrower than the diameters of even the smaller starch granules in the protein matrix. We discovered that, in the normal milling operations of commercial mills including the break steps and the later reduction steps, the starch granules will often remain intact while the previously adhering protein of the matrix having less cohesion will crack or break from the starch granules along the weaker lines and narrower portions between adjacent starch granules, thereby freeing a number of whole, discrete starch granules s while producing relatively small, very irregular shaped fragments of protein such as those indicated in FlGURES 1 and 2 by the letter p which have a number of concave curves or recessed in the periphery thereof, of a complementary shape to portions of the starch granules which previously were connected thereto.

In the case of soft wheat, the grindability is much greater as supported by leading authorities, as well as our own finding-s; the protein matrix is less hard and FIGURE 1 typically illustrates in particles E, F and G, the tendency of starch granules to overhang or protrude from the general edges of the protein matrix in which the same are imbedded with the softer protein matrix being worn or broken away between adjacent granules.

In the case of hard wheat flour particles illustrated in FIGURE 2, the nature of the protein material is much harder and the starch granules are more thoroughly imbedded and covered by the homogeneous protein matrix with the result that the general edges of the various particles or endosperm cell fragments are not scalloped by protruding of starch granules but are defined by more and rather sharp regular edges constituting principal portions of the protein mass or matrix.

Our microscope studies (with magnification up to 300 times) showed us that, in general, cereal flours are composed largely of three distinct types of discrete particles, to wit:

(l) The largest discrete particles (see FIGS. 1, 2, 6 and 7) are chunks or fragments of endosperm cells or, frequently, Whole endosperm cells or a large particle made up of two, side-by-side endosperm cells. (In the ordinary milling processes, largely roller milling, a single endosperm cell will disintegrate often into a very large number of different discrete particles.)

r'hese endosperm chunks, just like whole endosperm cells, contain the major constituents of flour, namely: starch granules, water-soluble carbohydrates, protein matter forming a matrix around the starch granules and some lipoids disposed in this protein matter while others closely surround the starch surfaces. This endosperm also contains enzymes somehow along with the protein matter, also vitamins, and minerals, while the exact location of these constituencies are not very Well understood. Another substance existing in endosperm is the cellulose endosperm cell Wall substance.

(2) A great number of free or discrete starch granules varying substantially in size and generally of ellipsoid form are present in cereal iiour stocks as may be apparent from study of FIGS. 1, 2 and 6 to 13, inclusive, and these discrete starch granules in the milling process and subdividing of the relatively large endosperm cells often become loosened from the protein matrix wherein they were originally imbedded. Frequently, small remnants of the protein matrix still will adhere to the surface of the free, discrete starch granules. Thus, they are not completely free of protein. Our illustrations show the existence of these adhering, micron protein substances.

(3) ln all milled, cereal iiour stocks, there are a great number of discrete, very small particles running by maximum linear measurement from two microns up to usually a peak of 24 microns. We have definitely discovered that substantially all of these minute particles, varying greatly in shape and having very irregular configuration with often arcuate recesses defining sides thereof are pure protein. When cutting, shearing or breaking occurs in the process of milling, the lines of adhesion of the protein matrix surrounding the starch granules are more usually broken than are the starch granules themselves so that, oftentimes, these small protein particles break off in the place and shape of the intervening protein matter between the granules as they were in the original endosperm cell.

Frequently small (2 to 8 microns) size starch granules get imbedded and arrested in the larger (l5 to 25 microns) protein fragment particles. Thus, the demarcation line between the three groups of flour particles is not sharp, but, on the other hand, is rather gradual but still exists. That is the reason why we show, for accomplishments, protein or starch concentration only and not purely separation.

The foregoing references to microscopic examinations and morphology of cereal particles beginning in column 8 with our surprising discovery of discrete protein-matter particles from novel processes of air separation are fully pointed out and explained in the exhaustive report of C. G. Harrel identified in the reports of Pillsbury Mills, Inc., our assignee, as ll-69 and entitled Fundamental Research on Flours Produced by Grinding and Fractionation.

The first classification of chunks or whole endosperm cells much more frequently occurs in hard wheats than in soft wheats. The largest starch granules found in cereal flour stocks range from 35 to 45 microns in major diameters which, we find, are centrifugally separated out by our critical vortex air separation at any cut below 52 F-D units. Endosperm chunks in which starch granules and protein matrix occur in the same proportion as they do in the parent wheat endosperm in hard wheat seldom are less than 50 microns in lineal average dimensions and average microns. Consequently, these will all stay in the coarse fraction of a 66 .F-D critical-cut separation. Generally speaking, the neutral criticalcut of a our is the index of what is the smallest size of endosperm chunk in which starch granules and protein matrix occur in the `same proportion as they do in the parent wheat endosperm.

The chart of FIGURE 3 of the drawings points out results and proofs obtained from careful sedimentation tests carried out under the said Whitby methods of centrifugal sedimentation and with the Whitby sedimentation apparatus upon a sample obtained from the fine (maximum) protein fraction of a soft wheat flour stock, air-separated through Ithe use of our novel methods at a critical-cut of 21 F-D units.

The lower portion of a Whitby sedimentation tube T is illustrated at the left in the chart on a greatly enlarged scale, having the diminished lower end thereof graduated upwardly from the bottom into millimeters. A por- -tion of the said sample was sedimented in accordance with the F-D method and tables and millimeter readings on the basis of settlement time for discrete particles approximating 20 F-D units, l0, S and 2 F-D units were considered exemplary and critical. Our object was to remove particles from the sedimentation chamber at the respective strata wherein, by our calculations of fluiddynamic standards, such values were present and to thereafter intensively observe and consider, under high magnification by microscope, the particles of each stratum. The applicant, Ralph Gracza, kept a careful notebook, tabulating all the results and findings and the results pointed out in FIGURE 3 are actually taken from said notebook.

First, after sedimentation, the lower chamber of the Whitby sedimentation tube T was carefully filled and then broken on the proper graduation (between 10 and 11 millimeters) to obtain a stratum of line particles of our 2 F-D unit elaluation. Some of said particles from such stratum were removed by a fine instrument and carefully spread over a slide. The ocular of the microscope was supplied with a measuring scale enabling the observer to read in linear microns and square micnons on the slide.

Similarly, the lower chamber of the tube was carefully filed and broken at the readings shown in the left on our chart and small portions of the stratum at the breaks removed for particles of SF-D units, 10 and 20 F-D unit evaluations, in each instance, the removed particles being carefully spread upon a separate slide as in the first instance. The respective slides, with the spread particles thereon, were intensively observed and frequently certain particles turned by us under a microscope having a magnification of 380 times actual size. Thereafter, the applicant Gracza from his observation of each slide under such magnification, drew in his notebook, to the best of his ability, enlargements of several actual particles for each stratum.

At the right-hand side of the chart, in great magnification (see the scale) of 1 to 1300, a typical protein particle and a typical starch particle for each of said stratas at the previously stated F-D unit evaluations have been reproduced.

The significance of the illustration is that the protein and starch particles side-by-side have identical flow` dynamic characteristics, i.e. common settling time. Generally a 61/2 micron average diameter ellipsoid starch granule with its 1.48 density behaves like the 13 micron long irregularly shaped 1.32 density protein-matter particle. Generally, the 9 micron starch behaves like the 18 micron protein; the 10 micron starch is similar in behavior to the 22l micron protein-matter particle. Generally, a critical-cut by How-dynamic Aseparation will treat protein matter twice the size of starch granules alike and grade them together into the same fraction of a separation. As explained beforehand, the total Weight of the less than 14 micron size starch granule is a very small portion of the flour stock and still a separation at that critical-cut is able to concentrate protein-matter particles up to 28 microns into the same fine fraction and that means all of the free, discrete protein and protein-matter concentrated particles available in the flour. This is a Well-grounded explanation, accounting for the high protein concentration by us through low critical-cut air separations.

More specifically, the difference in shape between protein-matter particles and starch granules having the same how-dynamic property (i.e. common resistance based on common `settling time) can be approached with numerical values called herein relative shape factors. These factors express how many times larger are the proteinmatter particles than the starch granules having both the same how-dynamic properties using in their expression procedure facilities made available by microscopic technique.

In Appendix C, Iattached to this specification, is a tabula-tion which should be referred 'to in conjunction with FIG. 19, presenting relative shape factor data based on careful selection of 40 particles.

EXAMPLES We will now give some examples of some of the practical uses of our processes. Hereinafter the ash, protein, moisture, fat, diastatic activity (maltose) and mold spore tests were all run according to standard methods as set forth in Cereal Laboratory Methods, fifth edition, 1947. The protein and ash figures hereinafter quoted were thereafter adjusted to a uniform 14% moisture basis. The cake and bread baking tests hereinafter quoted were carried out under standardized baking tests and the results tabulated in accordance with the previously identified authority, i.e. Cereal Laboratory Methods, fifth edition, 1947. There hereinafter quoted Fisher values were arrived at in accordance with the standardized method described in the publication of B. Dubrow, Analytical Chemistry, volume 25, 1953, pp. 1242 to 1244. Fisher Scientific Co. (Pittsburgh, Pa.) Directions for Determination of Average Particle Diameters, etc.

Example 1.-Singlestage air lseparation of a parent hard wheat patent iiour, commercially milled out of a blend of 50% hard spring wheat and 50% hard winter wheat containing 10.3% protein and 0.408% ash, and with a Fisher SSS value of 19.25.

The critical-cut of this separation was at approximately 22.5 F-D.

of the flour was obtained by such air separation as a fine particle-size fraction having a high, 20.6% protein and having 0.711% ash with a Fisher value of 4.0. The remaining 90% coarse fraction of the iiour contained 9.6% protein, 0.370% ash with a Fisher value of 20.4. The fine fraction is a high protein (commercially known as high gluten) our, well suited for blending purposes in order to make premium bakery fiours. The coarse fraction is a good family liour (for all purpose use).

In commercial milling, it is accepted practice to produce flour grades which are called patent flour, having rigid ash specifications .45% ash or less depending on whether the flour is a short or long patent fiour). Patent iiour usually comprises a blend of from twenty to forty millstreams in which the ash content of the individual streams ranges from 0.32% to 0.50% ash. When these streams are blended, the ash -content is averaged in the resultant blend and may approximate .40% ash as in the case ofthe parent tiour of Example 1. The other millstreams (from eight to fifteen), characterized by a relatively high ash content are not utilized in the manufacture of patent flour.

Example 1 (supra) shows removal through our processes from parent fiour stock containing .408% ash of a 10% fine fraction having a high ash content of the remaining patent tiour portion to .37% ash (90% of parent stock). This ash depletion has made possible the use for production of patent our of a number of said millstreams which previously were not used because of accepted ash specifications and which before our fractionation, contained more than .50% ash. Again, pointing to Example 1, we have found that on the basis of removal of 10% of the parent stock therein, having an ash content approximating .711% ash, we can utilize several additional higher ash millstreams to bolster the patent flour recovery. We have found that several commercial millstreams ranging between .50% and .60% ash can be included with the parent stock of Example 1 before processing and with our process, as carried out in said Example 1, result in a coarse fraction of the blend approximating .40% ash. Approximately 20% additional iiour stock by weight from the .50% to .60% ash streams can be utilized with the streams which make up the parent patent stock in Example l and when fractionated as set forth, will give a notable net gain in the patent iiour percentage in this example.

With further reference to the advantage of our novel processes in enhancing patent flour recovery, we have in actual use blended the ash depleted fractions of highash-content streams such as the fourth break flour, the first tailings and the seventh and eighth middlings fiour with the previously recognized twenty to forty, commercial, patent flour streams. In doing Ithis, the blend of the commercial high ash content streams with sometimes two or three streams of the higher ash patent stock, are usually rst subjected to a critical cut or cuts within the ranges of from l5 to 25 F-D, thereby separating out a fine fraction, usually constituting 3% to 8% of the said additional streams and having high ash content ranging from 0.9% to 1.5%. This leaves the larger fraction (from 92% to 97%) of the commercial higher ash content streams depleted of ash suliiciently for inclusion in commercial patent flour output, and said larger fraction may be merely added to the selected commercial patent our streams to produce a resultant blend having the desired ash content between 0.40% and 0.44%.

Example 2,-The production of two valuable our fractions by two-stage air separations from a commercially milled hard wheat patent iiour out of straight Nebraska winter wheat. The protein content was 10.08%, ash 0.371%, with a Fisher value of 18.2. The first-stage air separation was made at approximately 25 F-D with 15% by Weight, fine-particle fraction less than 25 F-D and an 85% coarse fraction.

The first-stage fine fraction contained 18% protein, 0.745% ash, with a Fisher value of 4.4. The first-stage coarse fraction contained 8.5% protein, 0.322% ash, with a Fisher value of 19.5.

We then made a second-stage air separation on the said coarse fraction at a critical-cut of approximately 64 F-D, and thereby divided the 85%, first-stage coarse fraction into a 33% second-stage fine fraction of from 25 to 64 F-D particles, and into a 52% secondstage coarse fraction containing the particles above 64 F-D (said last percentages being related to the total weight of the original or parent our stock).

The second-stage fine fraction contained 6.41% protein, and 0.344% ash, with a Fisher value of 13.75. It should be noted there that the protein was far below the level of the protein of the original parent stock. The second stage coarse fraction had a protein of 9.72% and an ash of 0.307%, with a Fisher value of 25.1.

We then blended -the first-stage fine fraction with the second-stage coarse fraction in the natural proportions enumerated (15% +52%=67%) for the production of 13 an excellent bread ilour having higher protein content than the parent flour stock, to Wit: 12.4% protein, 0.420% ash, with a Fisher value of 14.6. This blend, by test, baked a better bread than the original parent flour.

The second-stage fine fraction (33%) which was no part of the aforementioned blend is usable, for instance, as a blended part of a southern soft Wheat family or allpurpose flour, mainly utilized in biscuits and cakes.

For ready correlation lof description, protein, ash and Fisher, with cake volumes and bread volumes, the following table is reproduced from the results made in the previously described example.

2.-Exnm ple Cake 115% sugar, cc.

Volume Bread `Description Prot. Ash Fisher ol.

Parent flour XT-4923 18. 2 655 1st-stage coarse lus 25 F-D 1st-stage fine m 25 F-D )KT-4042-- 2nd-stage coarse plus 64 F-D r:KT-4953 nfl-stage tine plus 25-64 F-D XT- 49 54 Remix, X'r-lseo @Tassa-52% vand X'rasra "Example 3.-ln this example, a two-stage air separation was made with the identical parent stock of material specified in Example 2. The first-stage air separation was Carried out identical to the first-stage separation of Example 2 resulting in the previously noted protein, ash and Fisher valuations on the 15% first-stage fine fraction and the 85% first-stage coarse fraction.

en, in this example, a second-stage of air separation was made on the first-stage coarse fraction at a criticalcut approximating 53 F-D, dividing said 85% first-stage coarse fraction into a 22% second-stage line fraction (comprising particles between 25 and 53 F-D) and into a 63% second-stage coarse fraction containing the parti cles above 53 F-D.

The second-stage fine fraction contained 7.24% protein, 0.377% ash, with a Fisher value of 11.55. The second-stage coarse fraction had a protein content of 9.16%, ash 0.312%, with a Fisher value of 22.9.

We then blended the first-stage ne fraction (15%) with the second-stage coarse fraction (63%) producing a bread llour (78% of vthe original stock) with a higher protein content than the parent flour stock, to wit: a protein of 11.2%. This blended bread liour had an ash of 0.390%, with a Fisher value of 14.46.

Y The remaining portion, to Wit: the second-stage line fraction (22% by weight of the original stock) produced a good cake flour.

To facilitate correlation of the protein and ash content of the new fractions obtained in Example 3, as related to cake volume, the following tabulation is made of our results with reference to the second-stage coarse fraction and secondstage line fraction and the blend of the irststage line with the second-stage coarse.

Example 4.-Controlling cookie spread factor of wheat Hours by producing a coarser fraction flour through our novel air separation process. Within the range of our discovered critical-cuts, air separation has been found to lower the protein, make coarser the granulation and apparently remove most of the cell wall matter generally considered to be responsible for poor cookie spread.

In this example, a parent soft wheat flour with a protein content of 7.7%, an ash of 0.304%, and having a Fisher value of 12.25, was utilized, said flour having a cookie spread of 4.0" and an all-over quality evaluation score of 951/2.

We made a critical-air separation on this parent stock at a critical-cut of approximately 25 F-D resulting in a 19% tine fraction (by weight) and an 81% coarse fraction.

The fine fraction contained 19.8% protein and 0.382% ash, with a Fisher value of 4.55.

The coarse fraction (81%) contained 5.7% protein, 0.287% ash, with a Fisher value of 14.95. This coarser fraction was baked into cookies and the cookie spread was found to be 4%6". The overall baking quality score for the same was above 100, which score of the Quality Control Laboratories of Pillsbury Mills has been our standard of perfection.

We also report here that baking tests for Control of cookie spread were made on hard wheat flours inthe same manner with improvement by our air separation process on the coarse fraction for use in cookie baking. Recitation of such example is thought unnecessary in View of the similar results obtained and the fact that hard wheat flour stocks are not utilized or desired today in the production of cookie flour.

For reference concerning cookie baking and judging methods, we refer you to the article entitled Cookie Flour Studies I, Analysis by Means of the Cookie Test by G. F. Garnatz, W. H. Hanson and R. F. Lakamp, published in Cereal Chemistry, volume XXX, pp. 541-549, 1953.

Example 5.-Irnprovement of the baking quality ofv hard Wheat flours by the addition of high protein, line fraction of soft wheat flours (XT-5727 and )iT-5722).

A blend of 10W protein hard wheat family lour (which is not able to produce breads of large volumes alone because it is lacking in baking strength) and a fine air separated fraction from soft Wheat cake flour will produce breads with large volumes than a hard wheat our with the same protein content as such a blend.

The hard wheat family flour in this instance contained 10.5 protein, 0.402 ash, and was milled out of a mix of 35% Hard Spring Wheat and 65% Hard Winter wheat. The line fraction our in this instance was a by-product from commercial cake flour obtained through the co1nmercial application of our novel air separation process at critical cuts between 20 and 25 F-D. We show the specifications of such high protein line fraction tiours in the table below together with the making results from fluors blended out of the hard Wheat family flour with said line fraction ilours.

Percent of Percent of Loaf volfne fraction family flour ume of flour in in blend blend ec.

blend The family flour 0 100 730 Soft Wheat tne fraction' 10 90 735 Protein, 18.61%- 25 75 780 Ash, 0.45%- 50 50 810 Fisher, 4.7 75 25 845 Extraction, 5.0% 0 890 Soft Wheat ne fraction: 10 90 760 Protein, 22.16% 25 75 815 Ash, 0.44% 50 50 855 Fisher, 3.85-.. 75 25 900 Extraction, 9.0% 100 0 960 The said ne fraction (high protein product) was blendnormes ed variously with coarse grain flours such as graham and whole wheat and baking tests were made thereon. Also, the same high protein, soft wheat fraction of our invention was blended in various proportions with conventional blends of rye and clear hard Wheat fiours and we made baking tests to determine baked loaf volume, texture and dough handling properties. We found that the addition of said high protein, soft wheat fraction substantially improved in all instances above recited, the loaf volume, the texture of the loa and the doughehandling properties as contrasted with the coarse grain iiour per se in conventional rye and clear hard Wheat flour wherein such tests were made.

Example 6.-'he production of a better angle food cake flour out of the coarse fraction separated from soft Wheat cake ilour. In this example, we further show the removal of relatively high mold spore made from the parent flour stock and purposely used a parent soft wheat stock having a relatively high mold spore count.

The critical-cut was made in this instance at 16 F-D resulting in an 11.5% line fraction and an 8.5% coarse fraction. The objective in this case was the depletion of the protein and mold spore in the coarse fraction and in the production of a high protein level in the ne fraction. We tabulate below the results of this example.

The significant results from the foregoing are the depletion of lipoids (fats) as well as proteins and ash from the parent stock and into the hue fraction. The foregoing table definitely shows the concentration of the large proportion of the damaged starch and enzymes in the fine fraction as indicated by the maltose value shown. Our critical air separations furthermore concentrated the mold spores in the fine fraction, thereby depleting the mold spore content of the coarse fraction which materially enhanced the coarse fraction for prepared mixes. The depletion of lipoids and fats from the coarse fraction greatly enhances the value thereof as an angle food cake flour and as a portion of prepared cake mixes because the shelf life of the air-separated coarse fraction is very materially increased by such depictions (both mold spore and fat content).

Example 7.-Improvernent of rye our by depletion of protein, ash, damaged starch and fat from the parent stock.

The parent stock was a commercially milled white rye flour with a protein content of 8.45%, ash content of 0.716% and having a Fisher value of 10.25, and a color reflectance value of 36.1 Hunter color over the Color Difference Meter instrument, Rd measurements.

We employed an emcient air separation at 19.5 F-D critical-cut, producing an 8% fine fraction and a 92% coarse fraction.

The line fraction contained 17.6% protein, 1.15% ash with a 4.2 Fisher value, and 37.1 Rd reflectance by Hunter color difference meter.

The coarse fraction had 7.7% protein, 0.714% ash, with a Fisher value of 11.7, and with 33.9 Rd reflectance by Hunter color difference meter.

Note: The color reflectance was established by the system of color reflectance measurements of Pillsbury Mills, Inc., which system and methods are comparable to standard accepted methods as set forth in the publication Cereal Chemistry, volume XXXI, pp. 73 to 86 (1954), in an article entitled Evaluating Semolina Color 16 with Photo-electric Retlecto-Meter by F. A. Matz and R. A. Larson.

The Amylograph dough testing1 of the three ours (including the parent stock) utilizing gr. of flour and 450 cc. of water, showed the following:

Peak in B.U. Parent stock 965 Fine fraction 530 Coarse fraction -e p 2-2-1 980 Rye baking quality, as recognized, is generally associated with high Amylograph peak B U. values. The removal of the 8% ne fraction which had a low B.U. value has appreciably increased the high B.U. value of the coarse fraction.

Example 8.-Enhancing the bread baking qualities of a mediocre hard wheat bakery flour.

We produced flour fractions by two-stage, critical-cut air separations from a commercially milled, hard wheat patent flour consisting of a blend of 55% Oklahoma hard winter wheat, 30% North Kansas hard winter wheat, and 15% Montana hard spring wheat. The blend or parent stock had a protein content of 11.45%, ash of 0.407%, with a Fisher value of 20.7.

We made a first-stage air separation at approximately 34 FD critical-cut resulting in a line fraction of 10% by weight and a coarse fraction of 90%. The tiret-stage ne fraction (below 34 F-D size) contained 18.8% protein, 0.620% ash, with a Fisher value of 5.05. The first-stage coarse fraction had a protein content of 11.05%, ash of 0.389%, and a Fisher value of 22.5.

We made a second-stage air separation upon the coarse fraction (90%) at a critical-cut of approximately 72 F-D thereby dividing said 90% iirst-stage coarse fraction into a 21.5% second-stage line fraction (consisting of particles between 34 and 72 F-D) and into a second 68.5% coarse fraction containing the particles larger than 72 FD.

The second-stage fine fraction contained 9.72% protein, 0.403% ash, with a Fisher value of 12.6, obviously below the protein content of the original parent stock.

The second-stage coarse fraction had a protein of 11.6%, an ash of 0.365%, with a Fisher value of 26.4, the protein being obviously substantially higher than the original parent stock.

After the second critical-cut as enumerated, we blended the line fraction (high protein) of the first-stage with the coarse fraction of the second-stage air separation in their proportions (10% plus 68.5% equaling 78.5%), thereby producing a bread or bakery our with higher protein count than the parent llour stock, to wit: a protein percentage of 12.4, and having an ash of 0.403%, with a Fisher value of 19.95. We baked this flour into bread and found that a better bread was produced than from the original parent ilour.

The second-stage fine fraction (21.5% of the parent stock, by Weight, with protein content of 10.1%) which was no part of said blend was well usable, for example, as a blended part of a southern soft wheat family hour, the main use of which is for biscuits and cakes.

1t should be noted that the micro-photographs and illustrations appearing in the drawings of this application as FIGURES 7, 9, 11, 12 and 13 show the particle distribution and characteristics of the original parent flour (FIG- URE 7), the air-separated first-stage line (FIGURE 9), the coarse of the first-stage air separation (FIGURE ll) as well as the second-stage fine and coarse fraction (FIG- URES 12 and 13, respectively). The rst-stage ne iiour shown in FIGURE 9 well illustrates the general small size and the very irregular shapes of the free protein-matter particles. It also illustrates the relatively few numbers of small starch granules in relation to discrete protein-matter particles and the absence of larger starch granules.

The illustration (FIGURE l2) of the second-stage liney fraction of approximately 72 F-D critical-cut shows the preponderance of discrete, normal, average-size starch granules some of which have adhering protein matter thereon in relation to the ne-discrete protein-matter particles as well as to the endosperm chunks consisting of starch granules and the cementing protein matrix.

The illustration (FIGURE 13) of the second-stage coarse fraction is a good example o-f hard wheat endosperm chunks or chunk our particles as to general size, shape and morphology. All the pictures referred to well demonstrate the sharpness of separations made possible in the sub-sieve size ranges with our new process of critical-cut air separation.

Example 9.-Depletion of protein from soft wheat, short patent tlour (with attendant improvement in color by a second-stage critical-cut).

We utilized a commercially milled soft wheat patent iiour comprising a blend of 85% Northern Indiana soft wheat, 15% Michigan white wheat having a protein content of 7.7%, ash 0.304%, and with a Fisher value of 12.25, and with a Hunter Rd reflectance value of 64.1 and B yellowness value of +198.

We fractionated this soft wheat onr blend by air separation, for depletion of protein at a critical-cut of approximately 30 F-D, thereby producing a fine fraction coniprising 32% of the original stock and a coarse fraction comprising 68% of the parent stock. The said ne fraction contained 14.2% protein, 0.351% ash, with a Fisher value of 5.8, and a reectance value Rd of 63.1 by Hunter color difference meter, and a yellowness of B-l-19.0.

The coarse fraction trom said first-stage air separation had a protein content of only 5.3%, an ash of 0.284%, with a Fisher value of 16.55, and had a reflectance Rd value of 63.8 and yellowness B value of +192.

The coarse fraction (68% of lthe parent stock) as shown in FIGURE of the drawings makes an excellent angel food cake flour. The particle distribution is Well illustrated as in the parent stock in FIGURE 6 of the drawings and the iine portion is illustrated in FIGURE 8.

For certain uses to obtain even further depletion of protein and substantial improvement in color, We subjected a portion of the coarse fraction obtained in said previously recited rst-stage air separation (at 30 F-D critical-cut) to a second-stage separation at a critical-cut of 41 F-D, thereby dividing the coarse fraction into two second-stage fractions, the finer of which is approximately 40% or the weight of the coarse fraction, and the secondstage coarse fraction being approximately 55% of the first-stage coarse fraction.

The second-stage fine fraction contained only 4.02% protein, and 0.281% ash, with a Fisher value of 14.05, with a reectance value of 67.4 Rd and a yellowness value of Bal-17.6, the protein here being far below the level of the original parent stock. The color valuations expressed are significant in showing an enhanced lightness in the second-stage line fraction and a substantial reduction in yellowness as contrasted with both the parent stock and the previously produced fractions. The protein was far below the level of the original parent stock. The said improved fraction here (second-stage ne) contained par- |ticles between 30 and 41 F-D.

The second-stage coarse fraction (larger than 41 F-D) had a protein content or" 7.27%, ash 0.292%, with a Fisher value of 18.65, and having a reflectance value Rd of 61.7, and yellowness value B of +206.

The illustrations, FiGURES 6, 8 and 10, made from micro-photographs of the parent liour and the first-stage fine and coarse fractions, reveal the comparatively smaller average particle size of sof-t wheat tiour as contrasted with hard wheat iours. These illustrations also show the characteristic rounded or scalloped edges on the chunks or agglomerates of soft wheat particles as distinguished from the usually larger endosperm chunks of hard wheat delined by angulated, generally straight or angled edges without much overlapping of starch granules beyond the exterior edges of the protein matrix.

Example 10.-Up-grading the desirable qualities of corn llour.

(a) We obtained commercially produced yellow corn grits and, by commercial process, reduced it to ilour tineness, said flour having a protein of 7.82%, an ash of 0.306%, a maltose value of 114, 1.15%, with acidulated viscosity of and with color readings on the Hunter color difference meter for reflectance of Rd 44.4 and a yellowness of B equals +401 and with Fisher value of 21.7.

We have performed an eliicient air separation at approximately a 34 F-D critical-cut, thereby producing a 3% line fraction and a 97% coarse fraction. small tine fraction extracted, depleted the coarse fraction of protein, ash, maltose value and fat content containing, by our tests, 9% protein, 1.001% ash, 600 maltose value, 3.70% fat content, acidulated viscosity 70 MacM. degrees and color readings: reiiectarice Rd 47.6,

and yllOWllSS B e Hals 352 value 0f 6.15. q in and havmg a Fisher The coarse fraction from the tained 7.65% protein, 0.29% 150, fat content degrees, color readings: reflectance Rd 42.7 a

saine separation coriasli, a maltose value of with a commercially milled soft wh l eat, sh comprising a blend of Or'tpatentour wheat and 15% Michigan soft white whe aving a rotein con a Fisher vplue of ll'eit. of 7.7%, ash of 0.366% and A first-stage, eiiicient air se aration e the parent stock at 19 F-Ds Isind therea/itirmdseriiiIiiCi-.lIf stage air separation was made upon the coaise fraction n at '22 F-D. Thereafter, we made a third-stage air separation upon the second stage coarse (over 22 F-Ds) at a critical cut of 29 F-D. The tine fractions from said three air separations (at 19 22 and 29 F-D s) removed 28% by weight of the i'idur from the parent stock (smaller than 29 F-D).

i I fourth stage air separation at approximately 4l F-D critical cut, thereby producing a 13%, fourth stage tine fraction, consisting of .El Exnmiple 13.-Fractionation of soft wheat patent flourparticle distribution illustrated in FIGURES 16 to 18 of the drawings.

We subjected a commercially milled soft wheat, patent Z2 3) Production from milled cereal ours of a fraction having a relatively high concentration of starch.

(4) Production commercially from milled cereal ilours of fractions which have very low, protein content and flour comprising a blend of 85% Northern Indiana soft 5 which are adapted for sale as premium, cake-type ilours red wheat and Michigan white wheat to a singlefor making cookies, cakes, pancakes and other products stage air separation at approximately a F-D criticalmade from batters. cut. The parent iiour had a protein content of 7.83%, (5) Commercial production from milled cereal ours, ash 0.326%,andafat or lipoid value of 1.04%. selectively, of fractions which vary in protein content A critical-cut at approximately 20 F-D produced a line 10 from approximately 4% to approximately 26%. fraction comprising 12% by weight of the original flour (6) Removal from milled cereal ours of a fraction and a coarse fraction of 88% of the original ilour. having high concentration of substances producing ash. The line fraction contained 20.52% protein, 0.360% (7) Removal from milled cereal ours of a fraction ash, and a fat of 2.04%. rl'he coarse fraction contained havinga high concentration of lipoids. only 5.76% protein, 0.315% ash, and only 0.57% fat. 15 (8) Removal from milled cereal fiours of a fraction Physical dough tests were made on the parent flour and wherein the enzymes are concentrated. on both of its said fractions. We present below the results (9) Removal from milled cereal iiours of a fraction of said tests, showing characteristic indexes for the wherein damaged starch (the very tine or immature starch strength of the respective ours. granules and broken starch granules) are concentrated.

Extenso- Peak Amylo- Extensibility] Valorimgraph area Absorptime graph using resistance Description eter on relaxtion Farino- 65 gr. our based pn ation time graph and 460 ce. relaxation of 1 hour water B.U. oi 1 hour Parentnour 41 52.5 49.7 1.o 70o so/520=0.154 Coarse fraction.-. 32 80. 5 49. 1 0.5 745 63/400=0. 158 Fine fraetion se 135. 5 s2. e 21. o 455 124/700=o. 177

vPhysical dough testing data supports the contention of the example that the removal of the high protein fine fraction with great bread baking strength will reduce the strength of the remaining coarse fraction which is very desirable for a good cake flour. Valorimeter values reduced from 4l to 32, Extensogram area from 52.5 to 30.5, Farinograph peak time 1 to 0.5, Amylograph 700 to 745. The fine fraction displays extraordinary baking strength with 96 Valorimeter value, 135.5 Extensograph area, 82.9% absorption and 21.0 minute Farinograph peak time.

Exarrzple 14.-Production of two premium lour products from a single air separation of milled soft wheat ilour.

In this example, we utilized a commercially milled (bleach) soft wheat, short patent flour comprising a blend of 85% Northern indiana soft red wheat and 15% Michigan white wheat. r:This blend had a protein content of 8.05%, ash 0.303%, with a Fisher value of 11.4.

We subjected this iiour to eilcient air separation at a critical-cut of approximately 161/2 F-D resulting in the production or" a 6% ne fraction and a 94% coarse iraction.

The fine fraction (particles less than 16 F-D size) contained 23.7% protein, 0.429% ash, with a Fisher value of 3.68.

The coarse fraction contained only 7.6% protein, 0.307% ash, with a Fisher value of 11.7 and, upon tests, showed that this coarse fraction was well adapted for a protein-depleted improved cake liour. The rine fraction with the 23.7% protein constitutes a very valuable premium product or protein concentrate which is capable of many uses including blending of the weaker hard wheat or soft wheat flours to produce high grade bakery ilours.

From the foregoing disclosure and the several examples set forth, it will be seen that our inventions may be utilized to obtain, through dry fractionation and critical air separation, numerous valuable new results including the following:

(1) Withdrawal from milled cereal fleurs of substantially all discrete, protein matter particles.

(2) Production from milled cereal ours of a fraction of heretofore unattainable, high protein concentration constituting a premium product for the subsequent blending with or the upgrading of ours for baking purposes.

(l0) Production commercially of a large percentage, cereal our fraction having improvement in color (higher light reflectance).

11) Removal from milled cereal fleurs of a major proportion of microorganisms such as mold spores.

(12) Changing the physical dough characteristics and increasing or decreasing the baking strength as desirable for certain flour purposes, said characteristics including among others (a) absorption, (b) mixing tolerance, (c) valorimeter value, (d) amylograph peak, and (e) extensograph area.

(13) Increasing the possible patent flour percentage of commercial flour stocks through withdrawal of high ash contributing substances as well as other deleterious matter.

(14) Utilization of protein concentration steps as previously set forth in paragraph (2) with subsequent blending of the high protein fraction with lower protein wheat ilours (and consequently lower priced ilours) to produce standard, protein ilour grades. This advantage is applicable to the higher, protein soft wheat ours and the lower protein, hard wheat Hours which are commercially available.

(15) Blending or addition of our new high protein concentration fraction with wheat Hour mixes or blends recognized by the trade as mediocre quality as to protein and dough characteristics to thereby upgrade such mixes into standard and acceptable, quality ilours.

(16) Addition of our new high starch concentration fractions as previously set forth in paragraph (3) with wheat flour mixes recognized as mediocre quality for batter-type ours and thereby converting the same to quality iiours for such specic purposes.

(17) Increasing the shelf life of ilours and prepared mixes made therefrom by utilizing the combined elects of the preceding accomplishments numbered (7), (8) and (11).

(18) Creating new tiour types by blending selected fractions (of our invention) of soft wheat ilours with commercial hard wheat ours and also by blending fractions of our invention from hard wheat iiours with commercial soft wheat iiours to the end that the new products will better suit their ultimate uses and further, for substantial economy in the cost of the grain or our sources employed.

(19) Production of commercially milled, special flours with depletion of protein and ash producing substances and lipoids and with precontrolled flour particle size rangs (below the size of practical sitter separations) which produce better qualities in cake, cookie, pastry and other batter type ilours.

(20) Creation of new, mixed types of fleurs through the practice of our inventions by blending a selected concentrated fraction or a plurality of fractions (air separated in accordance with our inventive teachings) of different cereal flours such as rye, barley and wheat together or with one or more our streams commercially milled, to enhance baking qualities and edect economies in production.

Summarizing generally advantages for three important types of fleurs, we point out as follows:

BREAD FLOURS (Including Wheat Flours, Rye Fleurs and Blends of the Two) (a) Substantial economy in the purchase of grains for the production of standard, highly acceptable bread flours and notable increase in the patent tlour recoveries obtained therefrom.

(b) Improving quality characteristics including strength, volume, absorption, baking tolerance and color.

(c) Raising the protein content of commercially milled ours.

CAKE FLOURS (Including Layer Cakes and Angel Food) (a) Substantial economy in the purchase of grains for the production of standard, highly acceptable cake ours and notable increase in the patent llour recoveries obtained therefrom.

(b) improving the qualities including cake volume, shapes, absorption, color and texture.

(c) Lowering the protein content.

(d) Obtaining more suitable particle sizes.

The term cereal flour stocks as used in the claims herein is expressly understood to means liour stocks of the group consisting of soft wheat, hard wheat, white rye, dark rye and corn fleurs.

The present application is a continuation of our copending application Serial No. 470,244, filed November 22, 1954.

APPENDIX A-EXHIBT l Centrifuge Sea'menmtion Method for Particle Size Dszribution in "Flow-Dynamic Units INTRODUCTION IThe method described herein is used for the determination of a particular huid-dynamic property or characteristic of a test sample representing a material consisting of small particles. The property or characteristic to be measured is a function of three factors: (l) shape, (2) density, and (3) size. The numerical results cannot be unequivocally expressed in known units of measurement such as definite units of length (while the physical dimension of this characteristic is length) and, therefore, the result is expressed in terms of units which are arbitrarily referred to as dow-dynamic units. These units correspond only in a general way with what is regarded as the eifective diameter of the particle expressed in physical units of length such as microns. We do not attempt to measure directly effective diameter or effective size. The use of this expression would imply a measurement of particles which are spherical or of identical shape but with dilerent sizes. Wheat or other cereal flour particles have a wide diversity of shapes ranging from substantially spherical to particles having rnost irregular surfaces. The resistance of a particle to fluid-dynamic ilow will be the result of shape and size. The third particle characteristic, .e., density, iniiuences the magnitude of the propelling force. The purpose of the method herein described is the differentiation and comparison of the fluid-dynamic 2dproperty of particles moving in a liquid medium and the numerical expression of this property.

This method is an adaptation of known methods which have heretofore been employed for the measurement of particle size ln the known methods, the term size is expressed in units of length, and this value is intended to describe average linear diameter of an abstract, imaginary particle which is spherical, and by some parameter which is equivalent to other particles of quite different shapes. ln the present method, an assumption is made regarding the average shape of the particles in the calculation of the numerical ligures representing the fluiddynamic properties of the particles being examined. This assumption as to the average shape ofthe particles is introduced into the formula only as a practical aid in obtaining numerical results which very broadly approximate the average linear diameter of the particle in the tine sitter size range as observed under the microscope. As indicated before, the linear diameter is not a useful index when methods are employed for studying particles which vary tremendously in shape within any given samples and especially when the observer is concerned only with how the particles will behave when propelled through a uid by gravity or centrifugal force.

It is conceivable that two particles having diferent shapes, sizes, and densities may move the same distance in the same time through a given fluid medium when the balance of moving force to the resistance is the same. rl`he purpose of this method is to characterize these particles not in terms of shape or size or density, but by a numerical value based on the velocity with which the particles move through a given fluid under the influence of a force. The force of gravity alone was relied upon to move the particles by a method devised by K. T. Whitby and published in Bulletin No. 32 by the University of Minnesota (1950). An apparatus and method employing centrifugal force for the smaller particles was invented by Whitby and is disclosed and claimed in his co-pending application, Serial No. 329,411, tiled January 2, 1953, and assigned to Pillsbury Mills, Inc.

These methods take into account the fact that for very small particles, the viscous resistance of a fluid such as benzene is very great in comparison with the weight of a particle. Thus, in the case of a small particle moving downwardly under the influence of gravity, a speed is soon reached known as the terminal velocity at which the retarding force of viscous resistance is equal to the weight of the particle.

In the simple case of falling spherical particles, the following equation applies and represents Stokes law:

R=radius of the sphere, centimeters v=terininal velocity, centimeters per second v1=the coeicient of viscosity of the medium in which the sphere is falling; poise, grams per centimeter per second p=density of the particle, g./cm.3 p1=density of the medium in which the sphere is falling,

g./cm.3 1L-acceleration of gravity, gravitational constant, 980

cm./sec.2 Solving for terminal velocity we find:

9:2 915201-111) 9 11 In the case of wheat ilour particles, it is meaningless to use the term radius, and, therefore, we substitute the flow-dynamic measuring unit FeD, which corresponds to what diameter is (2R) in the Stokes Law equation.

Hence:

*18g (F D) n m (l) where 108 is introduced to convert the dimension of F-D from centimeters to microns.

To determine the flow-dynamic properties of a sample of material we utilize a method to be described in detail below, which is based on the above equation.

Gravity sedimentation in a liquid is employed to determine the percentage of particles having an F-D value of 0.0040 crn. or larger. lf a known distance is chosen and velocity expressed as T the equation takes on the following form:

1:7(p1) (F43)2 'fr FW (2) VIt is evident that there are only two variables, t and YF--D If, a time, t, is chosen, the size that falls a known distance, h, can be determined by solving the equation for F-D.

After the particles having an F-D value over 0.0040 cm. have settled out by gravity, centrifugal force is applied to accelerate the settling rate of the smaller parti cles remaining in the sedimentation liquid.

In the centrifuge sedimentation part of this procedure, a modified form of the above formula is used. The gravitational constant, g, is replaced by the centrifugal acceleration which is m2 where r is the variable radial distance between the rotational center and the location of the particle in the tube, w is the angular velocity of the centrifuge and is a constant. Substituting in the above equation, the following is obtained:

mtif-q 18X 10911 Separating the variables:

1s los, Q at lt- (1t-Dr (iT-po' 1- "Kr where K represents all the constants.

Integrating:

fidc-Kfr'l-KM o n r rr Rearranging:

If the time is chosen, the characteristic of the particle that travels a known distance can be determined by solving the equation for F-D.

The distance from the center of rotation to the top of the sedimentation liquid is r1, and r2 is the radius measured from the center of rotation to the bottom of the centrifuge tube generally.

In practice, the centrifuge portion is started after some settling has taken place by gravity. A correction `has to be applied since the small particles have settled some already. This has been done by correcting the time by the factor equivalent to the distance a particular particle has fallen measured in time.

There are different ways of taking this into consideration, one of which is to determine the position of the particle at the start of the centrifuge step and establish the r1 not to the top of the sedimentation liquid but at the position of the particle in the tube.

These two methods do result in differences in the first particle sizes measured by centrifuge, but the differences decrease as the particles measured become smaller.

HISTORY The sedimentation method for particle size distribution was studied in the 1948-1949 research of K. T. Whitby of the University of Minnesota under the sponsorship of the Millers National Federation. This work is published in Bulletin No. 32 of the University of Minnesota, 1950 (l). The outcome of this work was the adaptation of a Direct Weight Sedimentation Apparatus for use on flour mill stocks. This apparatus was used in Minneapolis Quality Control, Pillsbury Mills, Inc., in 19494950. Due to failure in attempts to overcome the objection to its cumbersome operation, it was abandoned in favor of the centrifuge technique which is still the standard test procedure in Pillsbury Milling Development. The Centrifuga Sedimentation Method started in June 1951.

The basic mathematics, physics, and assumptions are built on those published in the Whitby reference No. 1. The use of a shape factor parameter was carried over into the new Centrifuga Sedimentation Method with the modification that the assumed parameter (the Andreasons shape factor -Sk=l.612) is utilized only for the 40 flow-dynamic units and larger size particles. The sedimentation time of the 20-10-5 F-D unit size particles is computed with a shape factor of 1.0.

APPARATUS NECESSARY The following apparatus should be available for the performance of this test:

(1) One special centrifuge with two speeds, 600 and 1200 r.p.m. A description of such a centrifuge is available in Ref. No. 2, FIG. 1.

(2) One tube holder to permit reading during the gravity sedimentation portion of the test run. A mechanical tapper may be a part, or may not .be a part of this tube holder.

(3) Centrifuga tubes as described in Ref. No. 2, FIG.

(4) A dispersing chamber, also described in Ref. No. 2, FIGS. 4 and 5.

(5) Cleaning wire, brush, and powder scoop. The powder scoop has a large and small pocket especially adjusted to measure approximately the correct volume of material directly into the disbursing chamber, approximately 25 mg. and l0 mg. respectively. These amounts of test material fill the capillary on the bottom of the centrifuge tube to a final sedimentation height of 10 to 20 mm.

(6) Centrifuge sedimentation tables. Special time schedule tables are prepared for each material of known density (flour-4.44 gr./cc.) requiring a certain optimum sedimentation liquid of known viscosity and density.

(7) Appropriate sedimentation liquid with the viscosity and density known to 1% or better accuracy. Benzene is one of the best sedimentation liquids available for flour mill products, such as wheat flour, and is used in this sedimentation test. Benzene has a specific gravity of 0.8715, and a viscosity of 0.00582 poise at F.

8. Dispersion liquid. The specific gravity of the dispersion liquid should be at least 0.05 less than the specitic gravity of the sedimentation liquid. A mixture of 75% benzene and 25% naptha gasoline produces the best dispersing liquid for use wtih benzene as sedimentation fluid. By maintaining a specific gravity difference of 0.05 between the dispersing liquid and the sedimentation liquid, the intermixing of the two liquids is prevented and the dispersing liquid can be floated on the surface of the sedimentation liquid, and thus an even distribution of the particles of the sample on the surface of the sedimentation liquid can be assured.

(9) Stop watch and holder. An ordinary 60 second sweep stop watch is satisfactory.

`(10) Storage and dispensing containers for the sedimentation and dispersing liquids. An automatic pipette can be used to dispense the sedimentation liquid. Another convenient way to transfer the dispersing liquid to the dispersing chamber is by use of a medicine dropper.

(11) Data sheets.

METHOD OF OPERATION The test is normally carried out in the Afollowing manner:

A centrifuge tube is first cleaned with the sedimentation i liquid to be used. It is very important that no particles Stick to the walls of the tube to disturb subsequent sediseveros E? mentation tests. The cleaning wire and brush should be 11:10 cm., the height of the sedimentation liquid in the used after every test with benzene as the cleaning duid. tube, a constant.

rl`he properly cleaned tube is then tilled to within 6-7 p=l.440 gr./cm.3 the average speciiic gravity of flour, an mm. of the top with the sedimentation liquid and placed assumed constant here. in the tube holder. p1=0.87l5 grt/cm3 the speciiic gravity of benzene at The flour is dispersed directly into the chamber which 86 F., a constant. is small enough to cap with the nger tips. The screened g=980 cnn/sec?, a constant. end is considered the bottom. The following is the gen- F--D=liowdynamic units of size, microns. eral method of starting the sedimentation: SRL-.1.612 shape factor parameter.

(l) Place two level scoopfulls (small end) of our into the chamber.

(2) Add 0.8 ml. (approximately) of dispersion liquid.

(3) Shake vigorously :for 30 seconds, stop and release rifhe above formula is a mathematical definition of ow'- dynamic units.

The reading time schedule, Table II, for the centrifuge sedimentation part of the test is -derived from Equation 3.

PreSSllfe- After the introduction of the shape factor parameter here, (4) Cap the top W 1th a nger and remove nge from 15 the centrifuge sedimentation time for a certain flowbottom' dynamic unit is:

(5) Place chamber on the tube, release nger and start stop Watch. T um ML2( Sk): 5)

(6) Remove chamber with a twisting motion. This y (p-m)w2(F-D)2 71 will leave a sharp layer of dispersion liquid. Sk=L0 Shape faam, parameter If a tapping device is used, it should be started and the r1=3 4 cm readings of the sedimentation height on the bottom of ,2:1154 un,

the capillary are made according .to the time schedule. O h ,l th. f 1 t t. o ni a lf no mechanical tapping device is available, satisfactory ne s Ort Way to app y 1S 0mm a o ne rga Z t i. 25 tion of the time tablel schedule is explained in detail lsrn be Obtamed by hand tapping with a hght here. While the gravity sedimentation t1me schedule The particles settle through the sedimentation liquid readings are Fabula/@d mm-the beginnirig of ,the Sedi' in accordance with the principles of Stokes law and the mentaun this .centrifuge.Sedlinemauou lume sc nedfle 1S coarser particles will settle more rapidly than the ner gurd m ceninfuge Funmng um@ from the beginning of ones. The settling time of the coarser particles with only centrifuge sdlmemauon' The above formula giires the the force of gravity acting upon them is relatively short, cfnmfuge mme from the first beginning of the Sedlmnta and therefore particles down to approximately 40 ownon (Slme as grax/.1W sdlmeritatmn formlilm thremre dynamic units in Size are allowed to Seme Without apphh the basic formula 1s adjusted in the following manner: ing the centrifuge. When the gravity settling period has 18 1O17 1mg (ty-t0) been completed, the tube is placed in the centrifuge. The 3D p-p1)o2 (1T-DP r1 (ty) mentation tube with liquid. The centrifuge is run at the ntggstgie ttig! Specified Speed according to the time Schedule presented D After the calculation of the centrifuge times for the below. It is stopped at time intervals to make readings Y of the material height in the capillary bottom of the gaoalsl. only two ad'iustments must De made fof sedimentation tube. To determine the end point where (l) Adjust centrifuge times to compensate for ma@ rcllleOveim Sleeeungn {.le are Chosen ings taken at larger units (time clock settings). Note P i y Ly p S1 5 Table Il Where l0 units require 6l seconds but in practice TABLE I 12.2 seconds is used for 2O units so only an additional Time Table Schedule for Gravity sedimentation 48.8 seconds 1s requlred 1n going from 20 to l0 umts.

(2) Correction to compensate for starting (accelera- Ch n C l ht C 1 ht tion) and stopping (deacceleration) of the centrifuge.

OSG O O L Flow-dynamic units shape factor reading time, reading time, Thls musi be applied to eac-n Interval to be Observed' parameter seconds min. and sec. TABLE u glg Time Table Schedule for the Centrifztge Sedmentaton 1. 512 als C01. hp. 'rime clock 'rime einer 1.512 49.5 Chosen readingtirne, setting intersetting for L 612 77 l l, 1 Few-dynamic shape seconds vals for each cach test 1 612 137:0 2; 17 0 units factor uncorrected, test run, run (con L 612 198i) 3; 18:0 600 r.p.m. uncorrectcd rected +52 1. 612 309.0 5; os o Seconds Seconds 0 The reading times for the chosen units m Table I were 15 52; computed from a modiiication of Formula 2. The modi- 2` '-0 1950 2002 fied formula, including the shape factor parameter, is as follows:

1 The correction is necessary 'to compensate for thc errors introduced by acceleration and deaccelerntion periods in the test runs.

18X 10h17b s 5 min. 1,200 rpm.

Solving the equation for time (t):

(1r-Dn:

Gbserve that the height of the column of particies which have collected in the capillary narrowed bottom 18X lOlnh S )2 4 of the sedimentation tube is directly proportional to the (p-p1)g (F43)2 k 70 volume of the particles settled. Therefore, by taking For our .Lest the factors in this formula are: readings at'the time intervals listed in the above table and by noting the height of the column in the capillary, =t1me H1 SSCOHS we have determined the relative particle size distributions. 17:0.00582 viscosity of benzene in poise on 80 F., a conin the following table, we illustrate a typical particle size stent. distribtuion data sheet.

A plot is made on semi-logarithmic-three cycle paper using ow-dynamic units as the abscissa and percent liiner-than-size as the ordinate. The abscissa should be on the three cycle logarithmic side.

E@ represents a relationship as quoted by l. M. Dallavalle in his book Micronieritics, page 22, published (second edition) 1948 by Pitman Publishing Co. of New York city, New York.

Since for delinite d size particles on the path of a circle described by the radius R, forces are in equilibrium (CPl and DR) pointing in opposite directions (see FIG. 20) CR=DR Arranging the above relationships for d p particles. where:

d=critical diameter of sperical particle (cm.)

r p iluid=density of fluid (gn/cm3) p particle=density of particle (gr./cm.3) i' :radial velocity of duid and particle at critical radius (cin/sec.)

vT=tangential velocity of uid and particle at critical radius (cm/scc.)

(Note: From a practical Viewpoint, the diierences in the velocities of particle and fluid are negligible.)

R=crtical radius (cm.) e--Drag factor (no dimension) speciiied and measured CR: p particlesupplies a relationship which is taken from the law of kinetics.

For the radial component of flow dynamic drag 133:?, suicidi-Ree LIST Op REFERENCES by Dallavalle supra, quoting Wadell.

t 4 4 1 (a) \/e=0.63-4.8/\/Re for the total span of the (l) K. T. Whitby, Determination of Particle Size Dispractical Reynolds number range tribution, Apparatus and Technitiue for Flour Mill Dust. .(b) E:0'4 5 40/Re in the Reynolds number range- Bulletin No. 32, University of Minnesota. o

(2) K. T. Whitby, Method and Apparatus for Derer- 0 2 Re 500 mining Particle Size Distribution of Finely Divided Mate- ReziReynolds number (no dimension) defined as follows: rials. Patent application, Serial No. 329,411, tiled Jan- R .d d uary 2, 1953. 8:9 u1 'VR 0' APPENDIX B 3f p.=viscosity of iiiiid (gr./cm.sec.) n a l o n l) g u Explanation of Velocity and Force Condllons (With The foregoing presentation of formula has been avail- Force Conditions in Equilibrium) When Particles Are able from the authorities quoted as well as other authori- Subjected to Vortex-Type Air Separation ties, but to our knowledge, has not been used on a prac- In general vortex type, air classifiers as known from tical scale .to determine measurements of critical cut o the literature and authorities, use the following classiiica- 49 alf sepatratln Processs; We dld mke use )f 1t and fom tion principle: it helpiul in determining our various adjustments and A combined or resultant air ow of vortex .and Sink designs of efficient vortex air separating machines. iiows is created by some usually mechanical rotary or APPENDX C stationary means (cyclone). Particles of the material to l be classied are fed into and suspended in this vortex- Relmve 'Shape Fado'. Dat" sink ow. The following tabulation (which should be referred to `Referring to FlG. 20 of the drawings, in the plane in conjunction with HG. 19 of the drawings) presents perpendicular tothe axis of the vortex-sink How, velocity relative shape factor data based on very careful selecconditions change in such a manner that for a denito tion of 40 particles applying on them 60 actual measure- -d size patricle the radial component of the ow dyrnanic ments and after averaging and arranging data:

s di n 1 Particle r h e/ r/ A /A A a i i a co i ei l' r i it e mririllincrtlers umn sIt-Du Miron qiiiSic-bcn starh stqrcli5 l qs staieli units o-i 2o 10.6 11.1 1. 9s 1.87 o. 93 s. 7s 3. 52 i0 12.9 9.5 1.47 2.00 1.93 2. is 4.1

5 ii. i s. 5 1.50 1.80 1.45 2. 25 a. 27 2 i. o s. o 2. o 2. at 1.35 a. si 5. 2

Relative shape factor sub-averages 1. 76 2.0 1. 42 3.00 4. 02 Relative shape factor averages linear 1. 88 areal 2. 48

the explanation of FGURE NO.

seamos d equals the diameter of a circle of which area is equivalent to the projected area or" protein-matter particle at the position of maximum stabiiity (area shaded on FIG. 19), postulated.

Aqt equals the area of circle with 1 diameter, actually measured.

The proof of the very high, protein concentration achieved by our invention at previously unknown low critical-cut air separations is apparent from the foregoing, with the general explanation contained in columns 9 to l1 of the patent specification.

What is claimed is:

1. The process of producing a high-protein food product, said process comprising subjecting a cereal ilour consisting of a mixture of heterogeneous particles some of which consist principally of starch and others of which consist principally of protein and selected from the group consisting of wheat llour, rye flour and corn our, to an air current, fractionating said flour suspended in said air current at a cut above about 20 F-D units and below the neutral critical cut of the iiour being fractionated by suspending the ine fraction in one stream of said current and the coarse fraction in another stream of said current and separately collecting the tine fraction and the coarse fraction, and utilizing said tine fraction in the preparation of baked goods.

2. The process of producing a high-protein cereal our product, said process comprising subjecting a cereal flour consisting of a mixture of heterogeneous particles some of which consist principally of starch and others of which consist principally of protein and selected from the group consisting of wheat flour, rye flour and corn ilour, to an air current, fractionating said lour suspended in said air current at a cut above about 20 F-D units and below the neutral critical cut of the our being fractionated by suspending the line traction in one stream of said current and the coarse fraction in another stream of said current and collecting said fine fraction and then combining said collected tine fraction with a second cereal our lower in protein content than said collected tine fraction to fortity said second cereal flour in protein.

3. The process of producing a high-protein cereal our product, said process comprising subjecting a cereal our consisting of a mixture of heterogeneous particles some of which consist principally of starch and others of which consist principally of protein and selected from the group consisting of wheat flour, rye our and corn flour, to an air current, fractionating said flour suspended in said air current at a cut above about 20 F-D units and below the 5 neutral critical cut of the ilour being fractionated by suspending the tine fraction in one stream of said current and the coarse fraction in another stream of said current,

and then combining said tine fraction with a second cereal flour lower in protein content than said ne fraction to fortify said second cereal iiour in protein.

4. The process of producing a high-protein cereal our product, said process comprising subjecting a white rye cereal our consisting of a mixture of heterogeneous particles, some of which consist principally of starch and others of which consist principally of protein to an air current, fractionating said flour suspended in said air cur- 10 rent at a cut above about 15 and below 52 F-D- units by suspending the fine fraction in one stream of said current and the coarse fraction in another stream of said current, and then combining said line fraction with a second cereal our lower in protein content than said tine fraction to fortify said second cereal our in protein.

5. The process of producing a high-protein cereal our product, said process comprising subjecting a dark rye cereal flour consisting of a mixture of heterogeneous particles, some of which consist principally of starch and others of which consist principally of protein to an air current, fractionating said iiour suspended in said air current at a cut above about 18 and below 40 F-D units by suspending the tine fraction in one stream of said current and the coarse fraction in another stream of said current, and then combining said tine fraction with a second cereal iiour lower in protein content than said tine fraction to fortify said second cereal flour in protein.

6. The process of producing a high-protein cereal tlour product, said process comprising subjecting a corn cereal our consisting of a mixture of heterogeneous particles, some of which consist principally of starch and others of which consist principally of protein to an air current, fractionating said flour suspended in said air current at a cut above about 20 and below 36 F-D units by suspending the tine fraction in one stream of said' current, and the coarse fraction in another stream of said current, and then combining said ine fraction with a second cereal flour lower in protein content than said line fraction to 4 ortify said second cereal our in protein.

References Cited in the tile of this patent UNITED STATES PATENTS OTHER REFERENCES Cereal Chemistry, vol. 24 (1947), pages 381-393, pages 381-388 relied on.

Cereal Chemistry, vol. 25 (1948), pages 155-167.

Deutsche Mller Zeitung, No. 17 (1952), pages 417- 418.

vnf .......g 

1. THE PROCESS OF PRODUCING A HIGH-PROTEIN FOOD PRODUCT, SAID PROCESS COMPRISING SUBJECTING A CEREAL FLOUE CONSISTING OF A MIXTURE OF HETEROGENOUS PARTICLES SOME OF WHICH CONSIST PRINCIPALLY OF STARCH AND OTHERS OF WHICH CONSIST PRINCIPALLY OF PROTEIN AND SELECTED FROM THE GROUP CONSISTING OF WHEAT FLOUR, RYE FLOUR AND CORN FLOUR, TO AN AIR CURRENT, FRACTIONATING SAID FLOUR SUSPENDED IN SAID AIR CURRENT AT A CUT ABOVE ABOUT 20 F-D UNITS AND BELOW THE NEUTRAL CRITICAL CUT OF THE FLOUR BEING FRACTIONATED BY SUSPENDING THE FINE FRACTION IN ONE STREAM OF SAID CURRNET AND THE COARSE FRACTION IN ANOTHER STREAM OF SAID CURRENT AND SEPARATELY COLLECTING THE FINE FRACTION AND THE COARSE FRACTION, AND UTILIZING SAID FINE FRACTION IN THE PREPARATION OF BAKED GOODS. 